Conventionally, a system, in which when a receiving antenna gets close to plural transmitting antennas disposed, the position and posture of the receiving antenna is estimated, and power transmission is performed between a specific transmitting antenna and the receiving antenna, is known (for example, refer to patent literature 1). In a system disclosed by this patent literature 1, an existence detecting unit on a transmission side detects the voltage of each coil for power supply (transmitting antenna), and a positional posture estimating unit on the transmission side estimates the position and posture of a coil for reception (receiving antenna) on the basis of a result of the detection. Further, a table regarding the output power of an electricity-receiving device (receiving device) stored in a memory in advance. Then, a power supply control unit selects a power supply pattern, in which the output power of the electricity-receiving device is maximized, and supplies electric power, by referring to the table stored in the memory in accordance with a result of the estimation performed by the positional posture estimating unit. Thus, electric power can be supplied to the electricity-receiving device with a high degree of efficiency, regardless of the position and posture of the receiving antenna.